The field of this invention relates generally to latching assemblies, and more particularly to latching assembiles for cargo bracing devices used in cargo carrying vehicles.
Latching assemblies for cargo braces or bars are known. For example, U.S. Pat. No. 2,411,768 to Welch discloses a boxcar brace having a pair of oppositely sliding first and second members which engage opposite walls of a cargo carrying container. A handle having teeth is mounted to pivot on the first member. When the handle is pivoted, the teeth engage cooperating slots provided on the second member to move the members in opposite directions. A locking tip or protusion on the pivoted handle engages a latch provided on the second member to secure the handle and extended members in place. The pivotal handle is subjected to a considerable force from the extensible members of the cargo bar in order to maintain the members in an extended position. This force is transmitted to the latch assembly and particularly the pivotal mount for the movable latch element. There is, therefore, considerable stress on latch assembly pivot pins and mating openings which tends to fatigue the metal over time.
An additional problem is that debris can enter the latch assembly with resultant mechanical blocking of movement of the latch and/or corrosion of the pivotal mount. The high stress and corrosion often produce "freezing" of the movable latch element, making release of the latch very difficult.
Another example of a cargo bar latch assembly is that of U.S. Pat. No. 3,049,328 to Bishop. Two laterally displaceable members are telescoped within each other to move in opposite directions when a handle is pivoted. After the members have been placed into contact with opposite walls of a cargo carrying device, the handle is pivoted approximately 180.degree. to meet and slide past a spring-loaded latch. The handle is held in place by the latch, once the latch is passed, and the latch pops back into an extended position. Again this latch assembly is supported to move on a pin which must carry the full unlatching force on the handle. Additionally, the latch and spring are open to corrosion and other fouling which can cause the latch to freeze in place.
Since many cargo shoring applications are found in refrigerator trucks and rail cars, it is predictable that moisture will be present in such environments and will condense on metal members, such as the cargo bar latch assembly. In fact such assemblies often become literally frozen as a result of condensed, trapped and frozen moisture, and the presence of corrosive compounds, and particularly salts, causes corrosive freezing in addition to low temperature freezing.
When it is time to release such cargo shoring bars, they are seldom given time to thaw, and most latch release problems are handled by a blow from a hammer, wrench or other impact tool. This weakens the latch mechanism, and particularly the highly stressed pivot pin and generally greatly shortens the life of the cargo bar.